Main opposition party leader Moon Jae-in appointed three-term lawmaker Choi Jae-sung as secretary general of the New Politics Alliance for Democracy (NPAD), Tuesday.

Moon's decision came in the face of protests from some NPAD lawmakers, triggering a backlash from within.

He also made several other key appointments, including Rep. Ahn Gyu-baek as the head of strategy and public relations; Rep. Hong Jong-haak as the chief of digital communications; and Rep. Kim Kwan-young as deputy secretary general.

"The appointments were made in order to win the National Assembly elections next year," Kim Sung-soo, an NPAD spokesman said. "They are expected to take leading roles in party innovation to pave the way for the victory in the general election."

A factional rift is had made it hard for Moon to name a new secretary general, who will be in charge of getting the party ready for the 2016 elections.

Moon's choice for the post had been contested by NPAD floor leader Rep. Lee Jong-kul and those who wanted to see less of Moon's faction in the key positions.

The NPAD leader is regarded as a leader of a faction of lawmakers affiliated with the late former President Roh Moo-hyun's administration.

Choi has close ties with Chung Sey-kyun, a former opposition leader who served as commerce, industry and energy minister for the Roh administration in 2006 and 2007.

Moon was going to announce a new secretary general, Monday, but the announcement was delayed due to additional negotiations between Moon and Lee.

He wanted Choi in the position because he believes Choi will devote himself to efforts for "innovations" in the party that are being led by Kim Sang-gon, the head of a committee tasked with overhauling the party.

But those who oppose Roh's legacy and some party veterans were opposed to Choi.

"There are many in the party who fear that he does not represent the politics of unity and harmony," Chung Dae-cheol, an NPAD senior advisor said in a radio interview. "For the secretary general post, Moon should choose someone that does not invite division."

During a meeting late Sunday, Moon and Lee are said to have argued intensely over the choice of Choi. Lee reportedly described Moon's choice as "a move to break up the party."

Instead of Choi, Lee had suggested Rep. Noh Young-min, one of Moon's close aides, or Rep. Woo Yoon-keun, a former floor leader.

Because of the internal rift over the post, there were talks of inviting an outside figure.

"We had discussed the possibility of naming someone outside the party," Lee said.

The conflict over Moon's choice for secretary general shows his shaky leadership.

After the party's defeat in the April by-elections, Moon faced calls to resign. Since Kim was named to lead the committee to overhaul the party, Moon's status has diminished.

There is speculation that the party may split in autumn, if the committee concludes its term in September without any tangible outcome.

Some former and current members of the party from the Honam region, a stronghold of the NPAD, are said to be preparing to establish a new party.